-1001: ldr \rd, [\rx, #(AT91_DBGU_SR - AT91_DBGU)] @ Read Status Register
- tst \rd, #AT91_DBGU_TXEMPTY @ DBGU_TXEMPTY = 1 when transmission complete
+1001: ldr \rd, [\rx, #(AT91_DBGU_SR)] @ Read Status Register
+ tst \rd, #AT91_DBGU_TXEMPTY @ DBGU_TXEMPTY = 1 when transmission complete